This is the main puppet client. Its job is to retrieve the local machine's configuration from a remote server and apply it. In order to successfully communicate with the remote server, the client must have a certificate signed by a certificate authority that the server trusts; the recommended method for this, at the moment, is to run a certificate authority as part of the puppet server (which is the default). The client will connect and request a signed certificate, and will continue connecting until it receives one.

Once the client has a signed certificate, it will retrieve its configuration and apply it.+puppet agent+ does its best to find a compromise between interactive use and daemon use. Run with no arguments and no configuration, it will go into the backgroun, attempt to get a signed certificate, and retrieve and apply its configuration every 30 minutes.

Some flags are meant specifically for interactive use -- in particular, +test+, +tags+ or +fingerprint+ are useful. +test+ enables verbose logging, causes the daemon to stay in the foreground, exits if the server's configuration is invalid (this happens if, for instance, you've left a syntax error on the server), and exits after running the configuration once (rather than hanging around as a long-running process).

+tags+ allows you to specify what portions of a configuration you want to apply. Puppet elements are tagged with all of the class or definition names that contain them, and you can use the +tags+ flag to specify one of these names, causing only configuration elements contained within that class or definition to be applied. This is very useful when you are testing new configurations -- for instance, if you are just starting to manage +ntpd+, you would put all of the new elements into an +ntpd+ class, and call puppet with +--tags ntpd+, which would only apply that small portion of the configuration during your testing, rather than applying the whole thing.

+fingerprint+ is a one-time flag. In this mode +puppet agent+ will run once and display on the console (and in the log) the current certificate (or certificate request) fingerprint. Providing the +--digest+ option allows to use a different digest algorithm to generate the fingerprint. The main use is to verify that before signing a certificate request on the master, the certificate request the master received is the same as the one the client sent (to prevent against man-in-the-middle attacks when signing certificates).Note that any configuration parameter that's valid in the configuration file is also a valid long argument. For example, 'server' is a valid configuration parameter, so you can specify '--server servername' as an argument.

this is enabled, an exit code of '2' means there
were changes, and an exit code of '4' means that
there were failures during the transaction. This
option only makes sense in conjunction with
--onetime.

disable: Disable working on the local system. This puts a

lock file in place, causing +puppet agent+ not to
work on the system until the lock file is removed.
This is useful if you are testing a configuration
and do not want the central configuration to
override the local state until everything is tested
and committed.

+puppet agent+ uses the same lock file while it is running, so no more than one +puppet agent+ process is working at a time.

+puppet agent+ exits after executing this.

enable: Enable working on the local system. This removes any

lock file, causing +puppet agent+ to start managing
the local system again (although it will continue to
use its normal scheduling, so it might not start for
another half hour).

+puppet agent+ exits after executing this.

fqdn: Set the fully-qualified domain name of the client.

This is only used for certificate purposes, but can
be used to override the discovered hostname. If you
need to use this flag, it is generally an indication
of a setup problem.

help: Print this help message

logdest: Where to send messages. Choose between syslog, the

console, and a log file. Defaults to sending
messages to syslog, or the console if debugging or
verbosity is enabled.

no-client: Do not create a config client. This will cause the

daemon to run without ever checking for its
configuration automatically, and only makes sense
when used in conjunction with --listen.

onetime: Run the configuration once. Runs a single (normally

daemonized) Puppet run. Useful for interactively
running puppet agent when used in conjunction with
the --no-daemonize option.

fingerprint: Display the current certificate or certificate

signing request fingerprint and then exit. Use the
+--digest+ option to change the digest algorithm
used.

serve: Start another type of server. By default, +puppet

agent+ will start a service handler that allows
authenticated and authorized remote nodes to trigger
the configuration to be pulled down and applied. You
can specify any handler here that does not require
configuration, e.g., filebucket, ca, or resource.
The handlers are in +lib/puppet/network/handler+,
and the names must match exactly, both in the call
to +serve+ and in +namespaceauth.conf+.

test: Enable the most common options used for testing.

These are +onetime+, +verbose+, +ignorecache,
+no-daemonize+, and +no-usecacheonfailure+.

noop: Use +noop+ mode where the daemon runs in a no-op or

dry-run mode. This is useful for seeing what changes
Puppet will make without actually executing the
changes.

verbose: Turn on verbose reporting.

version: Print the puppet version number and exit.

waitforcert: This option only matters for daemons that do not yet

have certificates and it is enabled by default, with
a value of 120 (seconds). This causes +puppet agent+
to connect to the server every 2 minutes and ask it
to sign a certificate request. This is useful for
the initial setup of a puppet client. You can turn
off waiting for certificates by specifying a time of
0.